Integrated valorization of Sargassum muticum in biorefineries

Commercial Potential of Pelagic Sargassum spp. in Mexico

“…Surprisingly, the biomethane potential was slightly higher after the organic compounds were extracted, but anaerobic digestion of alginates has resulted in low biomethane production yields (Milledge et al, 2019). Overall, the work of Flórez-Fernández et al (2021) on S. muticum supports the biorefinery approach for obtaining a combination of high added-value products and bioenergy from sargasso, rather than using it only to produce biogas (a single product approach). Other authors have also stated that the only way that biofuel production from macroalgae would be economically attractive is to also produce marketable, high added-value products (Song et al, 2015;IEA-Bioenergy, 2017;Kumar et al, 2018;Rajak et al, 2020).…”

“…Information on biogas production from solid sargasso residues, following the extraction of high added-value compounds, is limited. At laboratory scale, the biomethane potential from the anaerobic digestion of the solid residue biomass (0.15 L CH 4 /kg total solids or TS) and fresh biomass of Sargassum mucticum (0.18 L CH 4 /kg TS) were very similar (Flórez-Fernández et al, 2021). Both biomasses were subjected to washing, grinding, freezing, and thawing; the solid residue was obtained after autohydrolysis at 150-170 • C, to extract alginates, fucoidans, and phenolic compounds.…”

“…In a sargasso-based biorefinery at least two conversion processes could operate, depending on the end products it seeks to deliver: chemical conversion to extract alginates and fucoidans, and biological conversion to produce bioenergy. Operational units such as grinding, heating, decanting, solvent extraction, and centrifuging would be indispensable for extracting the value-added products in the first step, and the final solid residue could be used for biogas production (Flórez-Fernández et al, 2021). Another option could be to extract the sugars through saccharification and use them for other purposes (Davis et al, 2020), such as ethanol production; in that case, a fermentation step is required, and the operational units necessary for recovering ethanol.…”

Opportunities Surrounding the Use of Sargassum Biomass as Precursor of Biogas, Bioethanol, and Biodiesel Production

“…Basic hydrolysis relies on using basic solvents to realize the cleavage of ether linkages in lignin and ester linkages between lignin and hemicellulose, resulting in lignin removal (An et al, 2014). Reports of increased ethanol yield from alginate-free Sargassum using a method of alginate removal with alkaline solution (Flórez-Fernández et al, 2021) hint at the possibility that the alginate extraction process acts as an alkaline pretreatment step and thus enhances bioethanol production.…”

“…The team worked with Sargassum angustifolium and unveiled that alginate extraction acted as a pretreatment of sorts for bioethanol production, yielding better results than fermentation that used the raw biomass directly. Flórez-Fernández et al (2021) worked with Sargassum muticum and concluded that alginate-free Sargassum showed better susceptibility to anaerobic digestion than raw algae. Fenoradosoa et al (2010) highlighted the relevance of the ratio between β-D-mannuronic acid and α-L-guluronic acid (M/G) in alginate.…”